Heat exchanger



Nov. 19, 1946. s. KOPP 2,411,436

HEAT EXGHANGER Filed March 3, 1944 f 59 FIG INVENTOR Sly mind kopp Patented Nov. 19, 1946 Sigmund Kopp, Glen Rock,

N. J., assignor to American Locomotive Company, New York, N. Y., a corporation of New York Application March 3, 1944, Serial No. 524,859

2 Claims.

This invention relates to heat exchangers, and more particularly to a condensate drain for a feedwater heater.

In conventional feedwater heaters, much of the heat exchange surface is often submerged in condensate, thereby reducing the efficiency of the eX- changer. Various attempts have been made to successfully drain off this condensate so that the maximum heat exchange surface is available. The present invention is directed to provide a more satisfactory drain for such condensate.

The object of the present invention is to provide an improved condensate drain for a heat exchanger.

Referring to the drawing forming a part of this application, Figure 1 is a section, taken on the line II of Fig. 2, ioreshortened, showing the heat exchanger of the present invention, parts being shown in full, and a pipe being indicated in dot-dash lines; Fig. 2 is a section on the line IIII of Fig. 1, only some of the tubes being indicated and parts being broken away to show a slot in one of the walls of the structure; and Fig. 3 is a section on the line III-III of Fig. 1, parts being broken away.

The present invention has application to various types of heat exchangers in which condensate collects in some portion thereof. A feedwater heater. with the channel at the bottom of the tubes, isan example of such a heat exchanger, and the following description, for simplicity, will be confined to such a feedwater heater.

The feedwater heater is indicated generally in thedrawing by the reference numeral I. It is vertically disposed and has a channel 2 and tubes 3, the channel being at the bottom of the tubes.

Channel 2 may be, as shown, a casting and has a cylindrical side wall 4 through which open, at opposite sidesthereof, a water inlet nozzle 5 and a water outlet nozzle 6.

A tube sheet 1, in which the tubes 3 are secured at their bottoms, closes the top of the channel and is cast with the wall 4. It extends circumferentially beyond the wall 4 providing a flange 8 having an inclined recessed bottom face 9. A similar flange it) extends outwardly from the bottom edge of the channel and. is provided with a face H similar to face 9 but oppositely directed.

A groove i2 is formed in the top face of the tube sheet 1 for coaction with a tongue l3 depending from a flange I 4 formed on the bottom of a shell it which is supported on top of the channel 2. A tongue 16 depends from the flange in for coaction with a groove H formed in the top face of a horizontal plate 18 closing the .top

ber 33 and nozzle 5 of a condensate receiver [9 to which the channel is secured. Plate I8 is extended circumferentially to the edge of flange I0 and is secured thereto by hook-shaped half rings 20, each of which has a flanged member 2| with an inclined face engaging face H and a plurality of set screws 22 threaded through the flange engaging the lower face of plate l8; and, when tightened, pulling channel 2 and receiver l9 into fluid-tight engagement.

The receiver I9 further includes a drain nozzle 23 at the bottom and a curved partition 24, depending from the plate ill to which it is welded. Partition 24 is also welded at its vertical edges to the side wall of the receiver, thereby providing a condensate drain duct or chamber 25 open at its bottom into the remainder of the receiver [9. An orifice 26 in plate l8 above chamber 25 connects chamber 25 with a chamber 2! formed in. channel 2 by a curved partition 28 concentric with partition 24 but of a smaller radius. Partition 2B is welded to the side wall and tube sheet of channel 2 and fits at its bottom in a groove 29 formed in the plate :8. An orifice 3!! in tube sheet 1 above chamber 21 connects chamber 2'! with the interior of the shell I5.

A partition 3| welded at the top to the tube sheet and fitting at its bottom in a groove 32 formed diametrally in the plate !8, partitions the channel in half forming an inlet chamber 33 and an outlet chamber 34, nozzle 5 opening into chamcpening out of, and partition 28 being disposed in, chamber 34. Shell l5 and channel 2 are secured together at their flanges l4 and 8 by half rings similar to the connection between channel 2 and receiver IS. The top of the shell is closed by a cover 35 connected to the shell [-5 by similar flanges and half rings. A steam inlet nozzle .35 opens into the upper end of the shell. 5

The tubes 3 are fastened at their upper ends in a tube sheet 3? which has an inclined recessed face 38 in its bottom peripheral margin, and a cover 39. providing a chamber 40, is secured to the tube sheet by hook bolts 4!. Tube sheet 3'! and cover .39 are freely disposed in cover 35 so that the tubes and tube sheet 37 may expand and con-.- tract freely relative to the shell 15, and no stresses will be set up in the feedwater heater due to such expansion and contraction.

An uncondensed gas and vapor chamber 42 is formed in the shell by a semi-circular horizontal wall 43 and two vertical walls 44 and 45, wall 45 depending from and being welded to the inner edge margin of .wall 43 and wall 44 being curved concentric with the shell and spaced therefrom ficed permitting the tubes 3 intercepted thereby to pass therethrough.

A condensate receiver vent pipe 48 is disposed in chamber 21 and at its bottom extends through orifice 28 into chamber and is fastened in partition 24, opening at its bottom end into the interior of the receiver l9 adjacent the plate l8:

Pipe 48 also extends through orifice and is connected by a union 49 toa curved pipe 50 which follows the wall of shell [5 adjacent the tube sheet i and extends through the slot 4l'opening into the chamber 42, thereby providing communication'between the chamber 42 and the receiver is for flow from receiver I9 to chamber 42 through pipes 48 and '50. Condensate from chamber 42 can return to the receiver l9 by flowing through the slot 41, the orifice 30, the cham. ber 21. the orifice 26 and the chamber 25.

Referring to Fig. 1, two openings 5! are shown in the center of the receiver l9, these openings being adapted for a condensate level gauge glass (not shown). An opening 52, in the wall of receiver I5 below nozzle 5, forms an uncondensed gas and vapor vent.

In order to maintain condensate in receiver ii! at a level above the bottom of the partition 24, thereby sealing same against the escape of steam into the receiver 49, a liquid level control apparatus, indicated generally by the reference numeral 53, is provided. It includes a control valve 54 secured to nozzle 23, and a float apparatus 55 disposed adjacent the outer wall of receiver 59 and" connected to the interior of the receiver below the bottom of partition 24 by a pipe 58. Thus condensate from the receiver it enters the float apparatus through the pipe 56. The float apparatus is vented to the interior of the shell 85 by a pipe 51 and is connected to the valve 54 for operating same bylinkage 58. The liquid level control apparatus is of a well-known type and no further description thereof is deemed necessary. Other suitable types of liquid level control apparatus may be employed if desired.

As it is necessary that the escape of steam be prevented by the bottom of the chamber 25 being sealed by condensate, when the exchanger is initially installed, the receiver l9 should be filled with water up to the desired condensate level, which is indicated by the dot-dash line a in Fig. 1. Or if desired, the linkage to the valve 54 may be secured in valve-closedposition until it can be seen in the condensate level gauge that condensate has collected to-the desired level.

The operation of the feedwater heater is as follows: Cold water ent'ers'the channel chamber 33 through nozzle 5, flows upwardly through the tubes 3 opening into chamber 33 and therefrom into chamber which acts as a return, directing the water to the remainder of the tubes 3 through which the water flows downwardly into chamber 34 and out of the exchanger through nozzle 5. Steam enters the shell through nozzle 36 and flows around the tubes, heating the water therein and being condensed as it is cooled by the water. .The condensate-from the steam drops to the bottom of the shell and passes through the orifice 30 into the chamber 21, from which it passes, by means of orifice 26, into the chamber 25 and therefrom to the condensate receiver Ill.

The condensate, collecting in the receiver l9, will raise the condensate level somewhat above the line a before the'fioatapparatus 55 will be effected enough to open the.valve"5 4 through the linkage 58. When the valve 54 is opened, the condensate in receiver l9 will partially drain off through the nozzle 23 so that the condensate will drop somewhat below the line a before the float apparatus once more closes the valve 54. Thus the draining off of condensate, as it continually drips into the receiver I9, will be periodical rather than continuous.

Uncondensed gas and vapor in the condensate escapes therefrom in the receiver l9 and passes into the pipe 48. The vent 52 acts as an auxiliary for any gas or vapor which does not escape throughthe pipe 48. The gas or vapor rises in the pipe 48, passes through the 'pipe 50 and is released in the chamber 42 around the coldest part of the tubes 3 passing through this chamber. It is here condensed, this condensate passing out of chamber 42 through the slot 41. If some gas or vapor is still uncondensed, it escapes from chamber 42 through the orifice 45 and therefrom through the vent 52'.

In the aforesaid operation, the vapor chamber 42 provides a zone around a portion of the tubes having the lowest temperature. This low temperature zone assures that non-Condensable gases, released through vent 52', will have a minimum of steam present. Moreover, the vapor chamber 42 also assures that non-conden-sable gases are passed over the tubes therein at a substantial velocity to obtain good heat transfer. Otherwise, the accumulation of non-condensable gases around the tubes would result in a substantial drop' in the heat transfer rate.

While the shell I5 may be Vented of non-condensable gases without the use of the aforesaid low temperature zone, such venting would release gases carrying out more steam than when the chamber 42 is used. Thus, this additional feature is beneficial in the use of such condensers where inflammable or noxious vapors are condensed since the sub-cooled gases passing through the vent 52' will have a smaller quantity of these vapors present than if a simple vent were used.

The vent 52, provided in the receiver I9, serves as an auxiliary vent to the vent 52' and is used only during starting or in an emergency. Fur-,

thermore, when the heat exchanger is inopera tion, the pressure in the vapor chamber 42 will be somewhat lower than in either shell l5 or re-' ceiver l9, and this difference in pressure induces fluid flow from both the shell [5 and the receiver l9 to the chamber 42. Thus, pipes 48 and 58 function as a vent from the receiver 18 and not as a steam feed from'the chamber 42 to the receiver l9.

While there has been hereinbefore described an approved embodiment of this invention, it will be understood that many and various changes and modifications'in form, arrangement of parts and details of construction thereof may be made without departing from the spirit of the invention, 7

and that all such changes and modifications as fall within the scope of the appended claims are contemplated as apart of this invention.

The invention claimed and desired to be secured by Letters Patent is:

1. Aheat'exchanger apparatus comprising a r vertical shell having an inlet for a condensable fluid; a tube sheet closing the bottom of said shell; tubes for a condensing fluid in said shell secured at their bottoms in orifices in said tube sheet a channel beneath said shell for said tubes provided with an inlet and an outlet for said tube fluid and having a bottom wall and having, as a top wall, said tube sheet; a receiver beneath said bottom wall; a conduit for conveying condensate and uncondensed fluid from said shell to said receiver opening at its top to said shell and opening at its bottom into said receiver at a point substantially below said bottom wall; means for draining said condensate from said receiver operable to maintain received condensate at a depth to keep said conduit bottom covered and to maintain a space in said receiver above said received condensate for said uncondensed fluid; and means for condensing at least a portion of said uncondensed fluid in said space including a relatively small low temperature condensing chamber in said shell, adjacent a portion of said tube sheet adjacent said channel inlet, through which inlet portions of at least some of said tubes extend, said chamber being open at its bottom to the bottom of said shell exterior of said chamber for flow of chamber condensate to said conduit, and a pipe connecting said space with said chamber for flow of said space uncondensed fluid to said chamber, said chamber being vented to the exterior of said shell for removal of uncondensed fluid from said chamber.

2. A heat exchanger apparatus comprisin a vertical shell having an inlet for a condensable fluid; a tube sheet closing the bottom of said shell; tubes for a condensing fluid in said shell secured at their bottoms in orifices in said tube sheet; a channel beneath said shell for said tubes having a bottom wall and having, as a top wall, said tube sheet, said channel being vertically partitioned providing a plurality of chambers with which said tubes connect, said chambers extending vertically throughout the entire space between said tube sheet and said bottom wall, one of said chambers providing an inlet for its correlated tubes and having a laterally disposed fluid inlet and another of said chambers providing an outlet for its correlated tubes and having a laterally disposed fluid outlet; a receiver beneath said bottom wall; a conduit for conveying condensate and uncondensed fluid from said shell to said receiver opening at its top to said shell and opening at its bottom into said receiver at a point substantially below said bottom wall; means for draining said condensate from said receiver operable to maintain received condensate at a depth to keep said conduit bottom covered and to maintain a space in said receiver above said received condensate for said uncondensed fluid; and means for condensing at least a portion of said uncondensed fluid in said space including a relatively small low temperature condensing chamber in said shell, adjacent a portion of said tube sheet above said inlet chamber, through which at least some of said inlet chamber correlated tubes at their inlet positions extend, said condensing chamber being open at its bottom to the bottom of said shell exterior of said condensing chamber for flow of condensing chamber condensate to said conduit; and a pipe connecting said space with said condensing chamber for flow of said space uncondensed. fluid to said condensing chamber, said condensing chamber being vented to the exterior of said shell for removal of uncondensed fluid from said condensing chamber.

SIGMUND KOPP. 

